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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Preparação e caracterização de dispositivos eletroluminescentes de complexos de β-Dicetonatos de íons Tb3+, Eu3+, Gd3+ com ligantes macrocíclicos e fimes de UO22+ / Preparation and characterization of electroluminescent devices based on complexes of β-diketonates of Tb3+, Eu3+, Gd3+ ions with macrocyclic ligands and UO22+ films

Gibelli, Edison Bessa 26 May 2010 (has links)
Complexos contendo íons de terras raras são de grande interesse na fabricação de dispositivos eletroluminescentes como é o caso do diodo emissor de luz construído com compostos orgânicos (OLED). Esses dispositivos, utilizando íons de terras raras trivalentes (TR3+) como centros emissores, exibem alta luminescência com bandas espectrais extremamente finas devido à estrutura dos seus níveis de energia, tempos de vida longos e a alta eficiência quântica. Este trabalho relata a preparação de complexos de β-dicetonatos (tta - tenoiltrifluoroacetonato e acac - acetilacetonato) de terras raras (Tb3+, Eu3+ e Gd3+) contendo ligante macrocíclico éter coroa (DB18C6 - dibenzo18coroa6) e de filmes poliméricos de UO22+. Os materiais obtidos foram caracterizados por titulação complexométrica com EDTA, análise elementar de CH, espectroscopia de absorção na região do infravermelho, análise termogravimétrica, difratometria de raios X (método do pó) e espectroscopia de luminescência. Na manufatura do dispositivo OLED construído neste trabalho utilizou-se a técnica de deposição física de filmes finos por fase vapor (PVD, Physical Vapor Deposition). / Complexes containing Rare Earth ions are of great interest in the manufacture of electroluminescent devices as organic light emitting devices (OLED). These devices, using rare earth trivalent ions (TR3+) as emitting centers, show high luminescence with extremely fine spectral bands due to the structure of their energy levels, long life time and high quantum efficiency. This work reports the preparation of Rare Earth β-diketonate complexes (Tb3+, Eu3+, Gd3+) and (tta - tenoyltrifluoroacetonate and acac - acetylacetonate) containing a ligand macrocyclic crown ether (DB18C6 - dibenzo18coroa6) and polymer films of UO22+. The materials were characterized by complexometric titration with EDTA, CH elemental analysis, near infrared absorption spectroscopy, thermal analysis, X-ray diffraction (powder method) and luminescence spectroscopy. For manufacturing the OLED it was used the technique of deposition of thin films by physical vapor (PVD, Physical Vapor Deposition).
32

Transition Properties of f-electrons in Rare-earth Optical Materials

Åberg, Daniel January 2004 (has links)
<p>The main purpose of this thesis is to theoretically study energy levels and intra-electronic transition intensities for various f-electron systems. The f-f electronic dipole transitions are parity-forbidden for a free ion but become non-zero when the ion is subject to a crystal-field. This is commonly described within the framework of Judd-Ofelt theory which accounts for the mixing of odd parity into the wave-functions.</p><p>Some refinements and quantitative studies have been made by applying many-body perturbation theory, or the perturbed functions approach, to obtain effective dipole operators due to correlation, spin-orbit and higher order crystal-field effects not included in Judd-Ofelt theory. A software for the computation of f-electron multiplets and Stark levels was implemented and published as well.</p><p>The single- and pair-functions used for the evaluation of intensity parameters were obtained by solving various inhomogeneous Schrödinger equations. The wave-functions and energies obtained by diagonalizing an effective Hamiltonian have been used together with the oscillator strength methods to simulate absorption spectrum. Consistent crystal-field parameters applied in some of the papers were obtained by fitting crystal polarizabilities to reflect the experimental Stark levels. The same crystal model was then used to generate odd crystal field parameters needed for the f-f transition intensities. The total effect of these refinements are spectral features that usually agree well with experimental findings. Some of these methods have also been applied and seen to be quite useful for the understanding of optical fiber amplifiers frequently used in today's optical networks.</p><p>Finally, a finite-difference approach was applied for the Helium iso-electronic sequence. The exact wave-function was expanded in a sum of partial waves, and accurate ground- and excited state energies were obtained by using the iterative Arnoldi approach.</p>
33

Transition Properties of f-electrons in Rare-earth Optical Materials

Åberg, Daniel January 2004 (has links)
The main purpose of this thesis is to theoretically study energy levels and intra-electronic transition intensities for various f-electron systems. The f-f electronic dipole transitions are parity-forbidden for a free ion but become non-zero when the ion is subject to a crystal-field. This is commonly described within the framework of Judd-Ofelt theory which accounts for the mixing of odd parity into the wave-functions. Some refinements and quantitative studies have been made by applying many-body perturbation theory, or the perturbed functions approach, to obtain effective dipole operators due to correlation, spin-orbit and higher order crystal-field effects not included in Judd-Ofelt theory. A software for the computation of f-electron multiplets and Stark levels was implemented and published as well. The single- and pair-functions used for the evaluation of intensity parameters were obtained by solving various inhomogeneous Schrödinger equations. The wave-functions and energies obtained by diagonalizing an effective Hamiltonian have been used together with the oscillator strength methods to simulate absorption spectrum. Consistent crystal-field parameters applied in some of the papers were obtained by fitting crystal polarizabilities to reflect the experimental Stark levels. The same crystal model was then used to generate odd crystal field parameters needed for the f-f transition intensities. The total effect of these refinements are spectral features that usually agree well with experimental findings. Some of these methods have also been applied and seen to be quite useful for the understanding of optical fiber amplifiers frequently used in today's optical networks. Finally, a finite-difference approach was applied for the Helium iso-electronic sequence. The exact wave-function was expanded in a sum of partial waves, and accurate ground- and excited state energies were obtained by using the iterative Arnoldi approach.
34

The Use Of N-polyethereal Polypyrroles In Preconcentration And Surface Enhanced Raman Scattering Studies

Koksel, Bahar 01 February 2009 (has links) (PDF)
Polypyrroles containing polyether pseudocages (PI, PII, PIII) have been synthesized via chemical oxidation of 1,5-bis(1,1-pyrrole)-3-oxabutane (MI), 1,8- bis(1,1-pyrrole)-3,6-dioxahexane (MII), and 1,11-bis(1,1-pyrrole)- 3,6,9-trioxaundecane (MIII) using anhydrous FeCl3 in CHCl3. Because as obtained polymer resins did not give any response toward any cations, they were reduced (undoped) using chemical reducing agents. Tetrabutylammonium hydroxide (TBAOH) was found to be more effective in undoping to obtain more reproducible and reusable polymer resins. It was investigated whether the undoped polymer resins were used for the extraction of rare earth metal ions from the aqueous medium. Among them, only PIII resin can extract La(III), Eu(III) and Yb(III) from their aqueous solutions and can be employed for the preconcentration of these metal ions. For batch extraction of La(III), Eu(III) and Yb(III) at neutral pH values, percent recoveries of 98.0, 90.7 and 87.3, respectively, has been obtained by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) technique. The sorption capacity is found as 1.3 mg of La(III) per gram of PIII resin. The PIII resin could be reused at least five times without significant change in its sorption capacity. PIII has also been synthesized via electrochemical method to be used in the preparation of Surface Enhanced Raman Scattering (SERS) active substrate. PIII has been polymerized on Indium Tin Oxide (ITO) glass by using constant potential electrolysis. In an electrolyte solution containing 0.05M tetrabutylammonium perchlorate (TBAP), 1.2 V vs. Ag wire (oxidation potential of MIII) was applied for coating and then silver particles were deposited on the surface of PIII coated ITO electrode by reducing Ag(I) in monomer free electrolyte solution electrochemically. As an alternative, another SERS substrate was prepared electrochemically by depositing silver particles directly on ITO glass. The performances of prepared ITO-PIII-Ag and ITO-Ag SERS substrates were evaluated with dilute solutions of brilliant cresyl blue (BCB), crystal violet (CV), para amino benzoic acid (PABA), nicotine and nicotinic acid.
35

Fabrication and characterization of ZnO film by spray pyrolysis and ZnO polycrystalline sintered pellets doped with rear earth ions

Al-Ahmadi, Ahmad Aziz. January 2003 (has links)
Thesis (M.S.)--Ohio University, November, 2003. / Title from PDF t.p. Includes bibliographical references (leaves 58-62).
36

Crystal-field splitting of Er³⁺ in ZnO and experimental observations

Cao, Kanyu. January 1997 (has links)
Thesis (M.S.)--Ohio University, August, 1997. / Title from PDF t.p.
37

Energies of rare-earth ion states relative to host bands in optical materials from electron photoemission spectroscopy

Thiel, Charles Warren. January 2003 (has links) (PDF)
Thesis (Ph. D.)--Montana State University--Bozeman, 2003. / Typescript. Chairperson, Graduate Committee: Rufus L. Cone. Includes bibliographical references (p. 361-380).
38

Síntese e caracterização de vidros de telureto dopados com íons de Eu3+ e Tb3+ com nanopartículas metálicas. / Synthesis and characterization of tellurite glasses doped with Eu3+ and Tb3+ ions with metallic nanoparticles.

Ricardo de Almeida Pinto 31 March 2009 (has links)
Neste trabalho são apresentadas a síntese e caracterização das propriedades luminescentes dos sistemas vítreos TeO2-ZnO e TeO2-ZnO-PbO-Na2O dopados com íons de európio e térbio contendo nanopartículas (NPs) metálicas de prata, ouro e cobre, para aplicações em dispositivos fotônicos. Estes vidros possuem uma larga região de transmissão (350-6500 nm), elevada estabilidade química, resistências mecânica e térmica, baixa energia de fônon (em torno de 700 cm-1) e alto índice de refração (~ 2,0). Por meio de medidas de absorção óptica foi observada a incorporação dos íons de terras-raras na forma trivalente, responsável pelo fenômeno de luminescência nos vidros e a presença de bandas de absorção relacionadas à ressonância dos plasmons superficiais (RPS), localizadas em aproximadamente 490 nm (no caso das NPs de prata), em 500 nm (no caso das NPs de ouro) e em torno de 800 nm (no caso das NPs de cobre). A caracterização das NPs metálicas foi realizada por meio da Microscopia Eletrônica de transmissão auxiliada pelas técnicas de difração de elétrons e espectrometria de energia dispersiva (EDS) e permitiu a observação de NPs metálicas, cristalinas e de diversos formatos e tamanhos. As medidas de emissão foram realizadas excitando as amostras em 405 nm para as dopadas com Eu3+ e 377 nm para as amostras dopadas com Tb3+, por meio de um espectrômetro de fluorescência, com lâmpada de Xenon de pulsos de 2 a 3 s. Foram medidas bandas de emissão associadas à emissão do Eu3+ em 580 nm, 590 nm, 614 nm, 650 nm e 695 nm devidas às transições 5D07FJ (com J = 0 até 4). A banda situada em 614 nm, associada a uma transição de dipolo-elétrico é a mais intensa, por ser mais sensível às mudanças do campo local provocado pela presença das NPs metálicas. Para as amostras dopadas com Tb3+ foram observadas emissões em 485 nm, 550 nm, 590 nm e 623 nm, associadas às transições 5D47FJ (com J = 6 até 3), sendo a emissão em 550 nm associada também a uma transição de dipolo-elétrico e portanto a mais sensível às alterações do campo local provocado pela presença das NPs metálicas. Para as amostras codopadas com íons de Eu3+ e Tb3+, foram observados aumentos significativos da luminescência referente à emissão em 614 nm na presença de NPs de prata. A obtenção de aumento da luminescência dos íons de Eu3+ somente pela transferência de energia proveniente do Tb3+ não é um mecanismo trivial. Entretanto, foi observado em amostras preparadas com diferentes concentrações de íons aceitadores e doadores e intensificada também na presença de NPs de prata. Os aumentos ocorridos na luminescência são provavelmente causados pelo aumento do campo local nas proximidades dos íons de terras-raras e por processos de transferência entre as NPs metálicas e os íons de terras-raras. Nestes casos a distância entre os íons de terras-raras e as NPs está compreendida entre 5 nm e 20 nm. Portanto, a presença das NP desempenha um papel importante para o aumento da luminescência, permitindo o desenvolvimento de novos materiais com aplicações em nanofotônica. / This work presents the synthesis and characterization of luminescent properties of vitreous systems TeO2-ZnO e TeO2-ZnO-PbO-Na2O doped with ions of europium and terbium containing silver, gold and copper nanoparticles (NPs), for applications in photonic devices. These glasses have a large window transmission (350-6500 nm), chemical stability, mechanical and thermal resistance, low phonon energy (around 700 cm-1) and high refraction index (~2,0). The optical absorption measurement showed the incorporation of rareearths ions in the trivalent form, responsible for the luminescence phenomenon in the glasses and the presence of absorption bands related to the surface plasmons resonance (SPR), located in approximately 490 nm (in the case of silver NPs) in 500 nm (in the case of gold NPs) and around 800 nm (in the case of copper NPs). The characterization of the metallic NPs was perfomed with transmission electron microscopy (TEM) with the aid of electron diffraction and energy dispersive spectroscopy techniques that allowed the observation of metallic NPs, crystalline with several shapes and sizes. The measurements were made through with excitation of 405 nm for samples doped with Eu3+ and 377 nm for samples doped with Tb3+, using a fluorescence spectrometer, with Xenon lamp with pulses varying from 2 to 3 s. The bands associated to Eu3+ emission were measured at 580 nm, 590 nm, 614 nm, 650 nm and 695 nm due to the transitions 5D07FJ (with J = 0 to 4). The band situated at 614 nm related to electric dipole transition is the most intense because it is sensitive to changes in the local field, caused by the presence of metallic NPs. For samples doped with Tb3+ it was observed emissions at 485 nm, 550 nm, 590 nm and 623 nm, associated with the transitions 5D47FJ (with J = 6 to 3) being the 550 nm emission also related to electric dipole transition and consequently the most sensitive to changes in the local field, caused by the presence of metallic NPs. For the samples codoped with Eu3+ and Tb3+ ions it was observed significative enhancement of the luminescence at 614 nm emission in the presence of silver NPs. The achievement of the enhancement of the luminescence of Eu3+ ions only by energy transfer from Tb3+ is not a trivial mechanism. However, it was observed in samples prepared with different concentrations of acceptor and donors ions and intensified in the presence of NPs silver. The enhancement of the luminescence is probably caused by the increase of the local field around the rare earth ions and by processes of energy transfer between the metallic NPs and the rare earth ions. In these cases the distance between the rare earth ions and the metallic NPs ranges from 5 to 20 nm. Thus, the presence of metallic NPs plays an important role for the enhancement of the luminescence, allowing the development of new materials with application in photonic.
39

Preparação e caracterização de vidros aluminato de cálcio com baixa concentração de sílica dopados com Nd2O3 e Er2O3 / Physical properties of low silica calcium aluminate glasses doped with NdO3 e Er2O3

Jurací Aparecido Sampaio 11 October 2001 (has links)
O desenvolvimento de laseres de estado sólido compacto operando na região do infravermelho médio, entre 2 - 5 ?m, tem recebido considerável atenção nos últimos anos. Esses dispositivos oferecem grande potencial como fonte de luz para uma infinidade de aplicações, como por exemplo laseres para medicina e sensores químicos remotos. Laseres operando na região de 2.8 ?m tem interesse particular na medicina devido a forte banda de absorção da água nessa região espectral. Para se conseguir forte emissão laser próximo a 2.8 ?m têm sido investigadas famílias de vidros não-óxidos, como por exemplo vidros fluoretos de metais pesados e vidros chalcogenetos, dopados com Er3+. Entretanto esses vidros são caros, difíceis de serem feitos, além de serem tóxicos. Por essa razão o desenvolvimento de um vidro óxido seria ideal, já que são mais baratos, relativamente fáceis de serem produzidos, além de não serem tóxicos. A desvantagem dos vidros óxidos é a sua alta energia de fônons, quando comparada aos vidros haletos e chalcogenetos, que aumenta a taxa de transição não radiativa. Seria interessante investigar um sistema vítreo que tivesse propriedades otimizadas, ou seja, boas propriedades ópticas, térmicas e mecânicas, e baixa energia de fônons. O sistema vítreo aluminato de cálcio seria um candidato para essas aplicações, já que preenche essas exigências. Porém não há na literatura informações a respeito da influência de pequenas quantidades de elementos terras raras nas propriedades desses vidros, e qual é a concentração ideal desses íons. O objetivo dessa tese foi investigar composições de vidros aluminato de cálcio (48,1 CaO : 40.8 Al2O3 : 4.1 MgO : 7.0 SiO2) dopados com Nd2O3, Er2O3 ou Yb2O3, e verificar qual a influência desses íons nas propriedades ópticas, térmicas, mecânicas e termo-ópticas. Investigou-se também qual a influência da atmosfera de fusão. Com esse objetivo as amostras foram fundidas em cadinhos de grafite sob vácuo, e em cadinhos de platina, ao ar, ambas as fusões ocorreram a 1400 °C. As amostras foram investigadas através de difração de raios-X e microscopia óptica, cujos resultados confirmaram o estado amorfo das amostras preparadas. As amostras não apresentaram estrias e tiveram boa transparência óptica. Os espectros de transmitância mostraram que o processo de fusão a vácuo eliminou completamente a forte banda de absorção próxima a 3 ?m devida a água. O corte da transmitância na região do infravermelho ocorreu em 5.5 ?m, sendo independente do tipo do íon terra rara presente na composição do vidro. O índice de refração em 546.1 nm aumentou de 1.6702 (amostra base) para 1.6876 (amostra dopada com 8% de Er2O3). Este acréscimo no índice de refração é atribuído a um aumento da polarizabilidade eletrônica do vidro devido ao aumento de oxigênios nonbridging. A densidade aumenta de 2.92 g/cm3 (amostra base) para 3.12 g/cm3 (amostra dopada com 8% de Er2O3), esse aumento é explicado levando em consideração a massa dos átomos terras raras, que são maiores em relação ao Al2O3. A dureza dos vidros aluminato de cálcio diminuiu de 865 kg/mm2 (amostra base) para 781 kg/mm2 (amostra dopada com 8% de Er2O3), ou seja aproximadamente 11% de decréscimo. No caso da temperatura de transição vítrea, Tg, esse decréscimo é de aproximadamente 8%, sendo 841 °C para a amostra base e 782 °C para a amostra dopada com 8% de Er2O3. Para o vidro base, a difusividade térmica foi de 5.75 x 10-3 cm2/s e a condutividade térmica foi de 15.5 x 10-3 cm-1 K-1. Tanto a difusividade quanto a condutividade térmica decresceram na mesma proporção da dureza e Tg, conforme substitui-se a alumina pelo óxido terra rara. Esta é uma indicação de que os átomos terras raras atuam como modificadores de rede, abrindo a estrutura do vidro, diminuindo a resistência mecânica e atuando como barreiras térmicas no material. A resistência ao choque térmico dos vidros aluminato de cálcio é de 339 W/m, semelhante aos vidros silicatos que é de 358 W/m, e aproximadamente quatro vezes maior que a dos vidros fluoretos, 86 W/m. Este resultado confirma a hipótese de que os vidros aluminato de cálcio podem suportar variações abruptas de temperatura. Através da espectroscopia de lente térmica foram obtidas a eficiência quântica dos vidros aluminato de cálcio dopados com Nd2O3 e Er2O3. No caso das amostras dopadas com concentrações menores de 3% de Nd2O3 a eficiência quântica foi de aproximadamente 80%. Esses resultados indicam que os vidros aluminato de cálcio são excelentes candidatos para laseres de estado sólido e demais aplicações ópticas na região do infravermelho médio. / The development of compact solid-state lasers operating in the midinfrared wavelength region (2 -5 ?m) has been an area of considerable activity in the last few years. These devices offer great potential as light sources for applications as medical lasers as well as in remote chemical sensing devices. Light sources in the 2.8?m region are of particular interest for medical applications due to the strong water absorption in this spectral region. Apart from allowing extremely precise cutting and ablation of water-containing tissues, the other advantages of using light sources operating at 2.8 ?m are related to the possibilities of reducing skin burning in surgeries, decrease in the use of anesthesia and shortening of recovery time, especially in skin surgeries and in the cutting and remova1 of hard tissues, such as tooth enamel and bone. In order to achieve strong laser emission around 2.8 ?m the effort so far has been concentrated on the family of Er3+ doped non -oxide glasses such as heavy metal fluorides and chalcogenides. However the production of these glasses is expensive, and it is difficult to make them, besides they are toxic. On the other hand, the oxide glasses are cheaper, atoxic and easy to produce them. The disadvantaged, however, is its the relative high phonon energy that promote high nonradiative transition rates. Since calcium aluminate glasses are formed with non-network forms, CaO and Al2O3, they have high tendence towards devitrification. The addition of small amounts of alkali and alkaline earth elements enlarges the glass forming region. Several calcium aluminate glasses compostions containing SiO2, BaO and MgO are now reported in the literature. In this thesis, low silica calcium aluminosilicate glasses doped with Nd2O3 and Er2O3 were prepared. Since the sample compositions were close to the phase diagram glass formation, the rare earth doping was performed up to 8wt.%. The samples was melted under vacuum condition in a graphite crucible at 1500 °C, and in air in a platinum crucible. The influence of the rare earth doping on the thermal diffusivity, thermal conductivity and Vickers hardness was such that all these physical parameters decreased by roughly the same amount, namely 8%, between the undoped and 5 wt% of Nd2O3. The dependence of these parameters, as a function of the Nd2O3 doping, strongly supports the idea that the Nd3+ or Er3+ act as network modifiers. Elastic module (E, G, K, v) of calcium aluminosilicate glasses with < 10 mole% of SiO2 doped with Er2O3 and Yb2O3, melted in air and under vacuum conditions, have been measured using the pulse echo ultrasonic technique. There was a decrease of the elastic properties, about 5%, as rare earth doping increases from 0.2 to 1.5-mol% (about 8 wt%). The Young\'s modulus did not vary within errors of measurements. The Debye temperature varied between (369±9)K and 352±9 K, which is explained assuming that the rare earth ions acts as network modifiers disrupting the glasses structure. The undoped calcium aluminate glasses fracture toughness is (1.4±0.3) MPa m1/2 and the thermal shock resistance is (339±102) W/m. The fluorescence quantum efficiency determined by thermal lens spectroscopy, was found be about 80% for the 2wt% Nd2O3 doped calcium aluminosilicate glass. The fluorescence quenching was observed to doping higher than 2wt% Nd2O3. The variation of the refractive index as a function of the temperature, dn/dT, was found be 8.0 x 10-6/0c. Among the various glass system investigated, CA glasses presented greater mechanical properties and larger thermal shock resistance, indicating that these materials are candidates for solid state laser applications and other infrared applications.
40

Síntese, caracterização e fotoluminescência de titanatos de cálcio dopados com íons Tm³+, Tb³+ e Sm³+ / Synthesis, characterization and photoluminescence calcium titanate doped rare-earth Tm³+, Tb³+ and Sm³+

Rastrelo, Lara Rossana 06 December 2013 (has links)
Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-16T19:39:29Z No. of bitstreams: 2 Dissertação - Lara Rossana Rastrelo - 2013.pdf: 2678778 bytes, checksum: 4329b26aff589960a1fe0857e0f08b6a (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: Mesmo que não encontre o autor no currículo latters use apenas as iniciais do no nome do autor na citação. Nas instruções das teses e dissertações aparece: Nome em citações bibliográficas - esta instrução será para o item 25º PESSOA, J. M. on 2015-10-19T13:44:33Z (GMT) / Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-19T17:01:38Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Lara Rossana Rastrelo - 2013.pdf: 2678778 bytes, checksum: 4329b26aff589960a1fe0857e0f08b6a (MD5) / Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: Mesmo não tendo currículo latters use o nomes do autor abreviado na citação, ou seja, no lugar de RASTRELO, Lara Rossana. Síntese, caracterização e fotoluminescência de titanatos de cálcio dopados com íons Tm³+, Tb³+ e Sm³+. 2013. 64 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2013. USE: RASTRELO, L. R. Síntese, caracterização e fotoluminescência de titanatos de cálcio dopados com íons Tm³+, Tb³+ e Sm³+. 2013. 64 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2013. on 2015-10-20T10:53:09Z (GMT) / Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-20T14:58:05Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Lara Rossana Rastrelo - 2013.pdf: 2678778 bytes, checksum: 4329b26aff589960a1fe0857e0f08b6a (MD5) / Approved for entry into archive by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-20T15:18:37Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Lara Rossana Rastrelo - 2013.pdf: 2678778 bytes, checksum: 4329b26aff589960a1fe0857e0f08b6a (MD5) / Made available in DSpace on 2015-10-20T15:18:37Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Lara Rossana Rastrelo - 2013.pdf: 2678778 bytes, checksum: 4329b26aff589960a1fe0857e0f08b6a (MD5) Previous issue date: 2013-12-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The photoluminescent properties (FL) has always aroused the interest of the scientific community, especially after the discovery of photoluminescence at room temperature, which favors applications in new optical-electronic devices. This work used the Polymeric Precursors Method to obtain CTO doped with rare earth ion: Tm3+, Tb3+ and Sm3+. The materials: CTO:Sm1,2%,Tb0,3%,Tm0,5% and CTO:Sm2%,Tb0,3%,Tm0,5% were calcined at temperatures of 450, 500, 550 and 600 ° C in order to correlate structural changes and photoluminescence emission. Other materials: CTO:Sm1,2%,Tm0,5%, CTO:Tm0,5%,Tb0,3%, CTO:Sm1,2%,Tb0,3%, CTO:Sm1,2%Tb0,3%, CTO:Tb0,3%, CTO:Tm0,5%, CTO:Sm1,2% and CTO:Sm2% were calcined at 600 ° C in order to comprehend the influence of rare earth ions in photoluminescence emission process. The structural organization of the materials over long distances CTO:Sm1,2%,Tb0,3%,Tm0,5% was correlated with the emission FL. The FL intensity can be linked directly to the structural system, and the material totally disorganized or completely organized does not present FL emission. The material CTO:Sm1,2%,Tb0,3%,Tm0,5% showed the highest intensity FL to materials heat treated at 500oC, while the material CTO:Sm2%,Tb0,3%,Tm0,5% showed the highest intensity FL to materials heat treated at 450 oC. The electronic transitions from rare earth ions was observed to the obtained materials. / A propriedade fotoluminescente (FL) sempre despertou o interesse da comunidade científica, principalmente a partir da descoberta da fotoluminescência a temperatura ambiente, o que favorece uma infinidade de aplicações em novos dispositivos óptico-eletrônicos. Neste trabalho sintetizaram-se pelo Método dos Precursores Poliméricos matrizes de CTO dopado com os íons Tm3+, Tb3+ e Sm3+. Os materiais: CTO:Sm1,2%,Tb0,3%,Tm0,5% e CTO:Sm1,2%,Tb0,3%,Tm0,5% foram calcinados nas temperaturas de 450, 500, 550 e 600ºC para a comparação de evolução estrutural e fotoluminescência. Outros materiais: CTO:Sm1,2%,Tm0,5%, CTO:Tm0,5%,Tb0,3%, CTO:Sm1,2%,Tb0,3%, CTO:Sm1,2%Tb0,3%, CTO:Tb0,3%, CTO:Tm0,5%, CTO:Sm1,2% e CTO:Sm2% foram calcinados a 600ºC para estudar a emissão apenas dos íons adicionados na matriz. A organização estrutural dos materiais a longa distância do CTO:Sm1,2%,Tb0,3%,Tm0,5% foi comparada com a emissão FL. A intensidade FL esta ligada diretamente ao ordenamento estrutural, se o material estiver totalmente desorganizado ou totalmente organizado não haverá emissão FL. O material CTO:Sm1,2%,Tb0,3%,Tm0,5% calcinado a 500ºC apresentou a maior intensidade FL. O material CTO:Sm2%,Tb0,3%,Tm0,5% quando calcinado a 450ºC apresentou a maior intensidade FL. Após a análise dos dados referentes à caracterização dos materiais foi possível atribuir às transições eletrônicas que ocorrem com os íons terras-raras e a influência da inserção de mais de um íon dopante na matriz titanato de cálcio na emissão FL.

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